Oral Streptococci growth on aging and non-aging esthetic restorations after radiotherapy

The aim of this study was to examine Streptococcus mutans biofilm growth on both aged and non-aged restorative dental resins, which were submitted to therapeutic irradiation. Sixty-four disks of an esthetic restorative material (Filtek Supreme) were divided into two groups: aged group (AG) and a non-aged group (NAG). Each group was subdivided into four subgroups: non-irradiated and irradiated with 10 Gy, 35 Gy, and 70 Gy. The biofilms were produced by Streptococcus mutans UA159 growing on both AG and NAG surfaces. The colony-forming units per mL (CFU/mL) were evaluated by the ANOVA and the Tukey LSD tests (a=0.05). AG presented smaller amounts of CFU/mL than the NAG before irradiation and after 10 Gy of irradiation (p<0.05). AG irradiated with 35 and 70 Gy showed increased amount of bacterial biofilm when compared to non-irradiated and 10 Gy-irradiated disks (p<0.05). The exposure to ionizing radiation at therapeutic doses promoted changes in bacterial adherence of aged dental restorative material. (author)